What is destroying sparkplugs in my engine?

hardparker

Private
Jan 23, 2018
29
Log it again and post up results. There's definitely still weirdness with cylinder two by looking at that plug. Combustion products seem to pass the threads on that plug more easily for some reason. I would scope it from the intake valve side, while the plug is out in order to inspect the plug hole where it enters the combustion chamber. I'm going to guess that the failed electrode earlier caused damage in the area around the hole where the plug protrudes. It looks a bit oily, too. That combined with the low compression may point to cracked or broken ring lands on the piston, possibly a result of that poor tune earlier. If that's the case, it will likely only get progressively worse in that cylinder. Monitor it with logs for a while to keep an eye on it.
 

sch4400

Lurker
Mar 20, 2018
13
Log it again and post up results. There's definitely still weirdness with cylinder two by looking at that plug. Combustion products seem to pass the threads on that plug more easily for some reason. I would scope it from the intake valve side, while the plug is out in order to inspect the plug hole where it enters the combustion chamber. I'm going to guess that the failed electrode earlier caused damage in the area around the hole where the plug protrudes. It looks a bit oily, too. That combined with the low compression may point to cracked or broken ring lands on the piston, possibly a result of that poor tune earlier. If that's the case, it will likely only get progressively worse in that cylinder. Monitor it with logs for a while to keep an eye on it.
well...
I think...you are right.
cause..I just forgot to post when I did leak down test.
all of cyl is ok..but.. when I did leak down test on cyl 2, there was leaky on spark plug hole.
I am a fool to forget that .

anyway what option should I have? replace the head?
 

Team503

Lurker
Nov 21, 2016
15
DFW
Can I threadjack a bit and ask a noob question? You guys say you see aluminum on the plugs - where do you see that? Is it the lighter speckles on the ground electrode?

Sorry, just a noob to this kinda thing.
 

martymil

Lieutenant
Free Vendor
Sep 6, 2017
797
Down Under
If there's a leak on cylinder 2 its most likely a ever so slightly bent valve or two from the broken electrode that previously broke off.

I think its time to take the head off and do a closer inspection

When you take it off you should be able to see where it was bouncing of the piston and head

Its the most likely thing that happen and thats why the spark plug colour is different to all the others
 

Rob09msport

Captain
Oct 28, 2017
1,052
Monroe CT
If there's a leak on cylinder 2 its most likely a ever so slightly bent valve or two from the broken electrode that previously broke off.

I think its time to take the head off and do a closer inspection

When you take it off you should be able to see where it was bouncing of the piston and head

Its the most likely thing that happen and thats why the spark plug colour is different to all the others
Could his crank hub have slipped?
 
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